The present invention relates to improvements in the manufacture and structure of reclosable plastic film bags, and more particularly a method of making a chain of reclosable bags wherein the bags are attached to each other in end-to-end relationship. In the advance of the art of the manufacture of reclosable bags, developments have led to the manufacture of chain bags wherein a continuous series of bags are attached to each other along their side edges and in the direction of the reclosable fastener for drawing the chain through machines which open, fill and reclose them or wherein individual bags can be removed from the chains.
This type of reclosable bag conventionally has a zipper top provided with facing ribs and grooves which are interlocked when a closing pressure is applied to opposing surfaces of the bag top. The bags can be opened for filling and again closed so that the eventual consumer has a reclosable bag.
Side-by-side bags and chains have been frequently used in manufacture because manufacturing processes frequently lend themselves better to making side-by-side bags. For example when the reclosable strip at the top of the bag and the bags are formed by a single extrusion operation, the bags and the fastener emerge from the die at the same time and cross-sealing provides side-by-side bags. Up to the present, it has not been possible to provide a chain of reclosable bags, made on an automated basis, where the reclosable fastener runs across the machine direction of the film, and where the bags, instead of being attached in the fastener direction, are attached above and parallel to the fastener. For certain purposes, this type of chain is preferable.
It is accordingly an object of the present invention to provide a new and improved method of the manufacture of a chain of bags wherein the individual bags are attached to each other in endwise relationship and wherein the top of one bag is attached to the bottom of the next bag and wherein the reclosable fastener extends laterally across each of the bags of the continuous chain.
A further object of the invention is to provide an improved method and bag structure wherein a chain of bags is manufactured by a new and improved process with improved steps accommodating themselves to rapid manufacture and making it possible to make bags from a continuous flat sheet of film.
In accordance with the principles of the invention, a continuous sheet or strip of film is provided which is doubled or foldable over itself to form a continuous bag body so that the bag body can be cross-sealed at predetermined intervals to provide individual bag bodies. The lateral aligned edges of the folded film are joined to provide a side seam for the bag. Prior to folding the film, a zipper of unique construction is attached laterally across the bag and the zipper has a plurality of ribs and grooves which will interlock with each other when the zipper is doubled or folded upon itself along with the folding of the film. Zipper material of this nature is known from U.S. patent application, Ausnit, Ser. No. 812,467, Filed Dec. 23, 1985. Lateral attachment of zipper material to strips has been known from U.S. patent application, Christoff, Ser. No. 837,161, Filed Jan. 30, 1984 and its parent application, U.S. Ser. No. 574,878.